Investigation of the Process of Simple Distillation in Irrigated Pipe Elements

Artem Sergeevich Ponikarov,Eduard Vladislavovich Osipov,Sergey Ivanovich Ponikarov

doi:10.3390/pr9112047

Artem Sergeevich Ponikarov, Eduard Vladislavovich Osipov + Show 1 more

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https://doi.org/10.3390/pr9112047

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Journal: Processes	Publication Date: Nov 16, 2021
Citations: 10	License type: CC BY 4.0

Affiliation: Kazan State Technological University

Abstract

In modern chemical and oil refining complexes, separation processes are among the most popular and energy-intensive. Installations for their implementation should be equipped with nodes for creating vapor (evaporators) and liquid (deflegmators) irrigation. Evaporators of any type (film, thermosiphon, gas lift, cubic) belong to this class of devices. For example, in cubic evaporators, the gas flow is completely formed from flux bubbles that originate on the heat-conducting surface and float in the volume of the cubic liquid located in the apparatus. Due to the accompanying mass exchange, the bubbles are enriched with volatile components during ascent and noticeably increase in volume, and the growth of the bubble is determined, among other things, by the total flow. At the same time, in real bubbling-type equipment, the total mass transfer surface exceeds the cross-section of the device itself by more than two orders of magnitude. Thus, according to, the ratio of the internal cross-sectional area of the apparatus to the developed mass transfer surface is 0.0015–0.002. Based on the analysis of the integral equation of the diffusion boundary layer, it is shown that the presence of a resultant flow of substance through the phase interface (non-equimolarity of the process) in a two-phase gas (vapor)–liquid system leads to the transformation of the structure of the traditional mass transfer equation itself. The use of a new structure obtained for both binary and multicomponent mixtures makes it possible to significantly simplify the approach to the description and generalization of arbitrary mass transfer processes. The innovativeness of the proposed approach lies in its universality for non-equimolar processes. This simplifies the creation of models of any mass transfer devices and entire production lines. In addition, the proposed approach is a good auxiliary tool for various researchers and experimenters. It should also be noted that the separation processes of many products of organic origin during heating are characterized by the appearance of undesirable side reactions (thermal decomposition, condensation, polycondensation, formation of harmful impurities, etc.), which occur most intensively in the heating zones. At the same time, the evaporation and distillation units are subject to requirements for the minimum hydraulic resistance of the structure, the maximum separation capacity (efficiency), and the minimum residence time of the product in the apparatus (equivalent to the minimum holding capacity of the structure). It was noted that the specified requirements are most fully met by film-type devices.

Highlights

In all cases, when using model No 2, the standard deviation was found be significantly smaller than when using special models developed only for the simple distillation process and only in the binary formulation of the problem. This fact confirms a certain universality of the proposed mathematical description and the expediency of its use for describing arbitrary non-equimolar mass transfer processes
The effects of non-equimolarity are determined both by the direction of convective mass flows (Nc ) and by the relations between Nc and the coefficients of equimolar mass transfer, which would be formed in the considered apparatus in a similar hydrodynamic situation (Re = idem, Sc = idem)
This relation for binary systems was previously called by us the non-equimolarity factor of the process, which can be considered as a similarity criterion that does not depend on either the type of the modeled process or its hardware design

Summary

Introduction

Under conditions of significant non-equimolarity in low-intensity flow regimes, the diffusion process in the corresponding phase can be completely blocked, and the mass transfer can be completely controlled by the diffusion resistance of another interacting phase, which in this case must be in a turbulent flow mode. These circumstances reduce the loss of calculation accuracy caused by possible errors in the calculation of mass transfer coefficients. Which was obtained in [26] on the basis of a numerical experiment on a mathematical model, and correlates well with the data of a number of researchers [21,22,23]

For the Liquid Phase

Mass Transfer in Irrigated Pipe Elements

Experimental Study of the Simple Distillation Process

Results and Discussion

Conclusions

Conventional Designations

Indexes